void main() {

  //Dart的运算符  +加 -减 *乘 /除 %其余 ~/取整


    int a =13;
    int b =2;

    print(a+b);
    print(a-b);
    print(a*b);
    print(a/b);
    print(a%b);
    print(a~/b);

  var c = a*b;
  print(c);

  //条件运算符 ==   !=    >   <   >=    <=


  int q = 5;
  int p = 5;

  print(q==p);
  print(q!=p);
   print(q>p);
    print(q<p);
     print(q>=p);
      print(q<=p);
  


print('========================');
//逻辑运算符

bool fs = true;

print(!fs);

bool fa = false;
bool fd = true;

print(fa && fd);  //fasle
print(fa || fd);  //ture


int e;  
e??=199;  //e为null 就赋值 199

print(e);


//符合赋值运算符  += -= /= %= ~/=

int r = 3;

r=r+7;

print(r);


int t = 90;

if (t>=90) {
  print('优秀');
} else if(t>=70) {
   print('可以');
}else if(t>=60){
  print('00');
}


var fat = false;

var g;
if(fat){
  g=fat;
}else{
   g=fat;
}

print(g);

///三目运算

bool  sm= false;

String msg = sm ? '真':'假';

print(msg);



int yy = 80;

String yymsg = yy  == 100 ? '真好，棒': yy == 80 ? '中上' : yy >= 60 ? '刚刚好':yy <60 ? "还得加油呢" : '失败' ;

print(yymsg);


int inu = 59;

inu = inu ?? 60;
print(inu); //59


int inu1;

inu1 = inu1 ?? 60;
print(inu1); //60



}